Interview with Dr. Mike Castellano - A Visit to the Kingdom of Truffles

Mushroom season will soon be upon us here in coastal CA, and that means the Santa Cruz Mycoflora Foray is on its way as well. We're real excited to have Dr. Mike Castellano joining us for the event – Mike is a world expert on sequestrate and hypogeous fungi (more on those terms later), and will be teaching both a workshop and giving a lecture about this group of fungi. It's been a long time since the truffles have had a thorough lookin' at in Santa Cruz County. We hope to learn a bit more about these organisms while Mike is in town.

Although Noah and I both got to spend quite a bit of time with Mike in April for the IUCN Macrofungi Assessment Workshop this spring, we didn't have much time to do anything other than work, so for myself as much as for newcomers to the world of mushroom identification, I think my interview with Dr. Mike Castellano will be of interest. Read on.

Tell us a about yourself: Where do you work? What do you do? How did you come to be interested in hypogeous fungi? How long have you been doing this?

Some rather rhizomorphic Hysterangium.

I grew up in the suburbs of Los Angeles in the late fifties and sixties and moved back to Long Island, NY in the late sixties. So, pretty much a city boy growing up, but I often went hunting in the Catskill Mountains of upstate NY. My college career, like many, started one way and ended up totally different in the long run. I started in accounting and ended up changing to forestry after a year and never looked back. I received a 2 year degree from Paul Smith’s College, and then returned to college to finish a BS on Forest Management at Oregon State University in the early 1980’s. I received a Forest Service intern position early on and meet Jim Trappe, the preeminent truffle expert. We hit if off as student/mentor and as friends, and I essentially followed in his footsteps, receiving a Master’s and PhD while working for the Forest Service. Early in my career with the Forest Service, I worked on mycorrhizal applications in nurseries and field planting, but by 1988 I was more or less a taxonomist/systematics researcher. My Ph.D. thesis was on the ecology and taxonomy of the truffle genus Hysterangium.

What are hypogeous fungi? How are they similar to more familiar mushrooms? Do they have similar ecological roles? How do they differ?

Hypogeous literally means hypo = below and geous = ground; so “below ground”, in reference to the habit of most truffles to produce the fruiting body/sporocarp below the surface of the soil. Common terms for this eclectic group of fungi are hypogeous fungi, sequestrate fungi, truffle fungi or even truffle-like fungi. The major differences from more typical mushrooms include: lack of active spore discharge from the basidia or ascus, enclosure of fertile tissue in a persistent peridium/covering, and/or convoluted and anastomosed tissue where the gills or pores would be.

Essentially this form is characterized by a distinct lack of wind dispersal as a mechanism for spore dispersal. These groups of fungi require that their fruitbodies be discovered and eaten by critters that then disperse their spores after passing them through their digestive tracts. The critters involved range from mice and squirrels to elk and bears to birds, lizards and even worms and beetles.

Ecologically, they serve in roles roles to many mushroom genera. Most truffle-like fungi form ectomycorrhizae with large woody plants; especially members of the pine, oak and eucalyptus families. But there are some truffle-like fungi that are saprobes as well.

Many truffle-like fungi are well know for their strong animal-attracting odors. I've smelled a fair amount of hypogeous species in my time, and can attest that there is a wide and bizarre range of smells. Do you have any favorites? Any least-favorites?

It is one of the wonderful benefits of collecting truffle fungi that many do indeed have interesting odors. I have pleasant memories of finding truffles while walking through the woods by first noticing a distinct smell; this most often occurs while collecting in the early morning on rather still days. I have personally attributed the following odors to specific truffle collections:

That sounds like a very complicated recipe for a rather unappetizing cake.

There’s a lot still to be learned about the identities of mushrooms in general, and truffle-like fungi are no exception. You’ve worked hard to introduce a tremendous number of new species to the scientific community, as well as some new genera and even whole taxonomic orders? That's pretty amazing. How many exactly? Can you give us some statistics?

I have been most fortunate to work with many people and therefore have access to many exciting specimens. Over the years I have been an author on descriptions of one new subclass, two new orders, over two dozen new genera, and over 200 new species. I have also had the good fortune to have two genera and one Tuber species named after me.

Those are some big numbers. Most impressive. Speaking of which, when Noah and I visited your herbarium during our IUCN conference in 2016, I think I speak for us both when I say that we were very impressed. Orderly and efficient, meticulously organized, yet super functional. Was it always that way? Or did you have a messy phase like Dr. Jim Trappe?

When I first started, I was amazed at how disorganized the lab was. It was about that time that I read The 7 Habits of Highly Successful People and took it to heart in all aspects of my own disorganized life. I then embarked on transforming chaos into order, if for no other purpose then to be able to find things quickly and reduce the frustration often associated with hunting around for that thing, specimen or item that you thought you knew where it was. Thankfully, Trappe embraced my efforts.

Speaking of Dr. Trappe, what is it like working with Dr. Jim? Any favorite stories?

Jim Trappe has been my employer, mentor, professor, friend and colleague since 1980. He is the most gentle and encouraging professor I have ever associated with in my 36 years in science. He is always the teacher, but while it is clear that he is extremely skilled, you never get the feeling that he’s lording it over you. As I’ve become more his colleague, and even in some realms of work his mentor, we’ve continued to draw closer together. It should be noted we have always had and continue to have disparate political and religious views, but this has never been an issue between us as colleagues or friends. I’m saving all the stories for my expose book on him… no, not really, but I often sprinkle stories about him into my presentations.

Left to right: Kris, Anders Dahlberg, Joey Spatafora, Jean Berube, and the Legendary Jim Trappe. Jim is lecturing us here about how chocolate cake is the perfect palate cleanser between beers. He was adamant.

You’ve spent quite a bit of time overseas looking for truffles. Tell us about some interesting habitats and ecological relationships you've encountered.

I've traveled to every state of the USA collecting truffles, and have been fortunate to collect truffles in about 20 different countries, including Australia, Papua New Guinea, Thailand, China, Chile, Sweden, etc. I particularly enjoyed my dozens of trips to Australia, during which I visited most of the forested regions along the perimeter of the country. Collecting in tropical Queensland was a real adventure: The forests are strung with huge spiderwebs that support bird-eating spiders, there are pythons in tall grassland, and there are land leeches in moist habitats tracking their way towards you as you hurriedly pick up specimens. Beyond the truffles, the myriad of exotic wildlife one encounters in the Australian bush is really special as well: from dingoes on Fraser Island to 7-foot tall Cassowaries in native forests, and of course the crazy and energetic Tasmanian Devils.

Truffloids can be really gorgeous.

You'll be joining us for the Santa Cruz Mycoflora Foray this December – we're excited to have you! What will you be looking for in the forests on the central coast? What do we have left to learn about hypogeous fungi in California?

California is incredible for truffle hunting. The vast diversity of habitats is staggering, and most of California is relatively untouched for discovering truffles. California is actually the home of the beginning of truffle discovery, dating back to the late 1890’s when Dr. Harkness collected extensively in the San Francisco Bay area and a bit in Yosemite. He published the first treatise of truffles from North America in 1899, based on his Californian collections. Since then, a few people have made some contributions: Parks, Setchell and Gardner in early 1900’s, Thiers, Saylor, and Menge in the late 1900’s, but relatively little has been done in California. I have tried to collect as often as possible, but even though I have nearly a thousand collections from scattered sites across California, and my herbarium has approximately 3,500 Californian collections, I routinely discover new taxa when collecting in the state. When all is said and done, I predict that we will find that California is home to at least 500 to 600 species of truffle-like fungi.

Once again, big numbers. That suggests that there’s a lot left to be done! Clearly amateur mushroom enthusiasts have a role to play in gathering this knowledge, but finding hypogeous fungi is hard. We look for places where squirrels have been digging, we use a hand rake to sift the duff, we squeeze suspicious-looking pebbles to make sure they’re not Gautieria… It’s tough. What are some tips and tricks you can share with to help us find these elusive fungi?

Hands full of Imaia gigantea truffles. Photo by Todd Elliott

Well now, if I told you then I would be revealing the magic! Actually, like most things, it is a bit of art mixed with a healthy portion of science. I’ll be teaching a specific workshop [at the SC Mycoflora Foray in December] entitled “What are Truffles and How Do I Find Them”. This gets people up to speed fairly quickly, and is always tied to a hands-on field trip where I specifically cover these principles again as we walk together in the woods.

Thanks to Dr. Mike Castellano for this interview – we're really looking forward to having him in Santa Cruz in December. Be sure not to miss out on his talks and workshop at the Santa Cruz Mycoflora Foray in December – register now using the button below!